Biological theories of religious belief are sometimes understood to undermine the very beliefs they are describing, proposing an alternative explanation for the causes of belief different from that given by religious believers themselves. This article surveys three categories of biological theorizing derived from evolutionary biology, cognitive science of religion, and neuroscience. Although each field raises important issues and in some cases potential challenges to the legitimacy of religious belief, in most cases the significance of these theories for the holding of religious beliefs is not very great